Almost 100,000 fit notes were handed out to patients in Cornwall last year, new figures show.
A fit note, which excuses someone from work due to sickness, can be issued after seven days of sickness absence if a doctor decides a patient’s health impacts their ability to work.
The doctor can decide if the patient is 'unfit for work' or 'may be fit for work subject to the following advice', accompanied by recommendations to help them in the workplace.
Responding to the figures, a public health charity has called for "decisive action" to keep workers healthy.
New figures from NHS England show 96,962 fit notes were provided by GPs in the former NHS Kernow CCG area in the year to June – an average of 8,080 notes a month.
These figures include every individual note written by a GP, rather than the number of patients receiving a note.
The notes were given out as part of 40,286 fit note 'episodes' – a period of sickness with one or more sick notes. Of these, 3,430 (9%) were for cases where a patient was given five or more notes in succession.
William Roberts, chief executive of the Royal Society for Public Health, said: "Today’s data reinforces the message that we will only be able to solve our productivity problem if we can take decisive action to keep employees healthy and in work."
He added: "This cannot be left to the NHS alone – businesses of all sizes and in all sectors need to step up and provide the support that their staff need, whether that is health checks, mental health support, or adaptations to ways of working."
Mr Roberts also called on the Government to introduce a minimum health and work standard, setting out the basic support which every workplace should offer.
Last month, Health Secretary Wes Streeting announced the Government is creating "crack teams" to tackle economic inactivity caused by long-term sickness.
He said the first 20 hospitals targeted by these teams will be in areas with the highest numbers of people off work sick.
"We will take the best of the NHS to the rest of the NHS, get sick Brits back to health and back to work," Mr Streeting added.
The figures show the number of fit notes issued across England dropped very slightly last year, with just under 11 million in the year to June. However, this remained above the 10.5 million handed out in 2021-22.
Nearly three quarters of the notes did not include a reason why the patient was given one. Despite this, mental and behavioural conditions were the most common reason among those that provided medical details – with more than 1 million issued in the year to June.
In Cornwall, at least 6,702 notes were given for this reason over the same period.
Separate data from the Office for National Statistics shows some 2.8 million working age adults across the UK were out of work due to ill health between May and July of this year, 700,000 more than at the end of 2019.
A spokesperson for the Department of Health and Social Care said: "We have seen record numbers of people excluded from the workforce due to long-term sickness and economic inactivity.
"The NHS and social care are a key part of economic growth - by cutting waiting lists and taking bold action on public health, we can get Britain back to health and back to work."